Thursday, February 24, 2011

Ammonites are an extinct group of marine invertebrates classified as cephalopods. Ammonites dominated the oceans at the beginning of the Mesozoic Era (250 million years ago). They are most-closely related to octopuses and squids, but with chambered shells similar to that of nautiluses. Because ammonites are extinct, and only their shells were preserved in detail, little is known about how they lived. Their chambered shells were filled with gas, which gave them buoyancy so they could live in the open oceans instead of on the ocean bottoms. It is thought that they ate a variety of small creatures that they could catch with their tentacles and swallow whole. They were probably a food source for some of the ancient marine reptiles, as ammonite fossils have been found with tooth marks left by such predators.

A 2-meter cast of the largest known ammonite

discovered in Seppenrade, Germany.

Many large ammonite fossils have been found in the riverbed of the Kali Gandaki Gorge in Nepal at elevations of up to 4,000 meters above sea level! These fossils were formed in the sediments of the Tethys Ocean 80 million years ago and uplifted as the Indo-Australian Plate collided with the Eurasian Plate to create the Himalayas. In India, some believe that ammonites symbolize the god Vishnu. Some Himalayan tribes refer to ammonites as the “Wheel of God” because of their spiral structure.The extinction of the ammonites has been attributed to the same asteroid impact that killed the dinosaurs 65 million years ago at the end of the Cretaceous Period. It is thought that they reproduced by laying a huge batch of eggs right before they died. These eggs rose to the surface as part of the plankton and were destroyed en mass by the violent effects of the asteroid strike. In contrast, nautiloids survived the mass extinction to evolved into present-day nautiluses. They laid their eggs in smaller batches on the sea floor where they were more protected from the asteroid impact.

Thursday, February 17, 2011

It has been more than 400 years since Galileo first pointed his telescope toward the heavens, and what he saw changed our world forever. Stephen Hawking is of the opinion that “Galileo, perhaps more than any other single person, was responsible for the birth of modern science.” Galileo was the first to observe the surface of the Moon in great detail, which he described as “full of cavities and prominences”. This was at odds with Aristotle’s view that the Moon and all the heavenly bodies were perfectly smooth. When he observed the stars through his telescope, he saw at least ten time as many stars as he could see without his telescope. He saw that nebulous clouds in the Milky Way were actually collections of many stars that were too small and close together to be seen individually with the naked eye.

The four Galilean moons with Jupiter,
comparing their sizes. From top to bottom:
Io, Europa, Ganymede and Callisto.

Galileo was also the first to view the four largest moons of Jupiter, now known as the Galilean moons: Io, Europa, Ganymede and Callisto. The discovery of celestial bodies orbiting something other than the Earth was at odds to Ptolemy’s age-old theory of geocentrism, which placed the Earth at the center of the universe with all the heavenly bodies orbiting around it. An even bigger blow to geocentrism came when Galileo studied Venus. He found that it went through phases, similar to the phases of the Moon. From this he reasoned that Venus must be orbiting the Sun. This evidence proved Copernicus was correct when he dared write—70 years prior—that the Earth and all the planets orbited the Sun. Heliocentrism may be taken for granted today, but at the time it was considered heresy. Galileo was eventually put on trial by the Inquisition and forced to recant his views. And even though he spent the last several years of his life under house arrest for his beliefs, the genie was already out of the bottle. No longer was man at the center of the universe—the Scientific Revolution had begun.

1) True or false: Using his telescope, Copernicus was able to view mountains and craters on the Moon.

Wednesday, February 9, 2011

The movie Jurassic Park is generally regarded as a landmark film in the way it depicted dinosaurs with its computer-generated special effects. But they got a couple of things wrong in how they portrayed Velociraptor, the film’s main protagonist. Fossil evidence tells us they were not nearly as large as what was represented in the movie and that they should have had feathers—a discovery that wasn’t made until after the move had already been released.

A cousin to Velociraptor was discovered in 2002 in northeastern China. Named Microraptor for its small size (it weighs in at only about one kilogram), this fossil—both strange and beautifully preserved—has added fuel to the debate over the origins of flight. You see, this 130 million-year-old creature had four wings.

Close up of the feathered hind legs of Microraptor.
Photo courtesy of David W. E. Hone, et al.

It is believed that birds evolved from dinosaurs about 100 million years ago, but exactly how has been a mystery. Microraptor, with its bird-like wings, dino tail and long, aerodynamic feathers attached to its feet, could be a missing link. Some paleontologists believe that Microraptor was a glider similar to a flying squirrel, leaping high off trees and gliding with its long back feathers over its tail to produce additional lift, then bringing its hind legs forward to create a second set of wings, similar to an old-fashioned biplane, as it slowed and pulled up to land on another tree. This challenges the previously-accepted notion that flight developed from fast-running dinosaurs with feathered arms that evolved into wings and eventually propelled them in flight.

And while the jury is still out on whether this dinosaur is a missing link to birds or just an evolutionary sideshow, it is clear that as more feathered dinosaurs are discovered, we will eventually find out whether or not birds, like airplanes, evolved from four wings to two.

Tuesday, February 1, 2011

The National Assessment of Education Progress (NAEP) recently released the results from its national science testing for grades 4, 8 and 12. The results are not good: 29% of fourth-grade students, 38% of eighth-grade students and 40% of high school seniors performed below a basic level in science while only 1-2% performed at an advanced level in any of the three grades. It’s especially troublesome that the scores got worse as the grade levels increase.

One possible reason for this trend is the emphasis we now place on reading and mathematics, both of which are part of the No Child Left Behind Act (NCLB). While its good that our children are getting more of the basics, it’s coming at a cost. Many schools are deliberately cutting back on science instruction because its not part of NCLB. And because funding is tied to NCLB, most states have been forced to make budget cuts in non-tested school subjects such as science and other programs, as well as books, field trips and school supplies.

What can we do about it? We have to take our children’s education into our own hands. If our children are not getting what they need from our schools we have to supplement it. Its my experience that kids love science—they just need the exposure. A trip to the library can work wonders at spurring a kids innate desire to learn.

We also need to voice our concerns with our school boards and school administrators. President Obama has made it clear that he is not a fan of NCLB as it is currently structured so lets hope it gets a good overhauling soon. Let your representatives know what you think. So instead of a quiz today lets do some homework instead.